System and method for storing communications intended for different groups using a limited amount of space

ABSTRACT

A system and method stores wirelessly received communications for wireless retransmission, making space in a storage device, if necessary, by deleting any one or more communications corresponding to the same group as the received communication. If storage in the storage device remains insufficient, communications that have been previously retransmitted by that same device are deleted, according to one or more characteristics of such stored communications, such as age or number of times an instance of that communication has been received. If storage in the storage device remains insufficient, communications of a different group are deleted according to one or more characteristics of the stored communications.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of and claims priority toU.S. application Ser. No. 13/465,379, filed May 7, 2012, which is acontinuation application of and claims priority to U.S. application Ser.No. 12/002,612, filed Dec. 17, 2007, entitled “System and Method forStoring Communications Intended for Different Groups Using a LimitedAmount of Space,” now U.S. Pat. No. 8,176,223, issued May 8, 2012Further, this application is related to U.S. application Ser. No.11/698,358, filed Jan. 26, 2007, entitled “System and Method for Sendingand Receiving Scalable Acknowledgments” and U.S. application Ser. No.11/698,334, filed Jan. 26, 2007, entitled “System and Method forReceiving and Sending Scalable Acknowledgments”. The above-referencedapplications are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention is related to computer software and morespecifically to computer software for wireless devices with limitedmemory.

BACKGROUND OF THE INVENTION

The related applications describe an arrangement whereby wirelessdevices are divided into groups of devices. Each group is assigned alieutenant, the devices in the groups provide acknowledgements tocommunications to the lieutenant for the group, and the lieutenantforwards a report of the acknowledgements it has or has not received.The devices may receive communications from their respective lieutenantsor from other devices.

There may be other reasons that devices are grouped. In the event thatsome communications may be commands, each device may be assigned as adevice that is to perform only certain commands, or the device may beonly capable of performing some commands but not others. To facilitatethe performance of only certain commands, commands may be sent with oneor more group identifiers, and each device performs the commandscorresponding to a group identifier of that device. The group identifiercorresponding to the device may be part of the device, for example,being stored in ROM, or it may be dynamically assigned and reassigned asneeded.

As described in the related applications, each device receiving acommunication rebroadcasts the communication to the other devices inrange of that device, allowing devices to receive a communication evenif they are not in range of the device that sent the communication.

It may be desirable to allow devices to receive and rebroadcastcommunications that are not for the group to which the device isassigned. In this manner, the range of communications is extended forall devices.

It may also be desirable for a device to request the most recentcommunication for the group to which that device is assigned. The otherdevices in the same group can store the most recently receivedcommunication or communications for the group and rebroadcast it inresponse to such a request. In this manner, a device that does notreceive a communication within an expected period of time can send sucha request and receive the communication.

However, there is a problem with this approach. To be able to respond tosuch a request from devices assigned to groups other than the group towhich the device receiving the request is assigned, that device muststore the communications for all of the groups it can receive. If thedevices that receive and rebroadcast the communications have a limitedamount of storage, the storage of communications solely for the purposeof responding to the occasional request from another group can take asignificant amount of the storage capacity of the device. This storagecapacity may be needed by the device for other purposes.

What is needed is a system and method that can store communications forother groups without interfering with the storage needs of the device.

SUMMARY OF INVENTION

A system and method receives communications for various groups,timestamps and stores each communication and an identifier of the groupto which the communication is directed. To make room for the receivedcommunication, other communications from the same group may be deleteddepending on the characteristics of such other communications, forexample in order to attempt to maintain in storage the most recentcommunication for many groups, though other numbers of communicationsfor each group may be stored. Communications may be received in multipleinstances, and the number of instances a communication is received ismaintained.

The system and method rebroadcasts a stored communication when such acommunication is requested by another device. When a communication for agroup other than the group to which the receiving device corresponds isrequested, the system and method also marks the communication as havingbeen sent, in addition to rebroadcasting the communication.

When the incoming communication is received, the amount of storageavailable is checked to determine if the incoming communication can fitin the available storage, if any currently stored communication for thesame group is first deleted or if communications from the same grouphaving other one or more characteristics are first deleted. There maynot be any such stored communication, or the incoming communication maybe larger than the deleted one or more communications for the samegroup. If an insufficient amount of storage is available to store anincoming communication, the marked one or more communicationscorresponding to one or more characteristics, such as the one or moreoldest marked communications, or the one or more communicationsindicated as having been received the most number of instances, aredeleted to make room for the incoming communication, and the processrepeats from the check of the amount of available storage. If sufficientstorage is not available after all marked communications meeting thecharacteristic or characteristics have been deleted, unmarkedcommunications for groups other than the device receiving thecommunication may be deleted, starting with the oldest of suchcommunications, the one having been received the most number ofinstances, or one or more communications meeting other characteristics.If insufficient space is available after deleting such communications,an error is identified.

The present invention thus prioritizes communications that have alreadybeen rebroadcast in response to a request once as the lowest priorityfor retention, with ties being broken to delete the oldestcommunications, communications having been received the most number ofinstances, or communications received matching other characteristicsfirst. Such a priority arrangement accommodates the fact that if two ormore devices did not receive a communication, the rebroadcast inresponse to the first request is likely to have been received by anyother device that did not receive the communication, and thus, thatcommunication is less likely to require a subsequent rebroadcast.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block schematic diagram of a conventional computer system.

FIGS. 2A, 2B and 2C are a flowchart illustrating a method of storing andproviding communications according to one embodiment of the presentinvention.

FIG. 3 is a block schematic diagram of a system for storing andproviding communications according to one embodiment of the presentinvention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention may be implemented as computer software on aconventional computer system. Referring now to FIG. 1, a conventionalcomputer system 150 for practicing the present invention is shown.Processor 160 retrieves and executes software instructions stored instorage 162 such as memory, which may be Random Access Memory (RAM) andmay control other components to perform the present invention. Storage162 may be used to store program instructions or data or both. Storage164, such as a computer disk drive or other nonvolatile storage, mayprovide storage of data or program instructions. In one embodiment,storage 164 provides longer term storage of instructions and data, withstorage 162 providing storage for data or instructions that may only berequired for a shorter time than that of storage 164. Input device 166such as a computer keyboard or mouse or both allows user input to thesystem 150. Output 168, such as a display or printer, allows the systemto provide information such as instructions, data or other informationto the user of the system 150. Storage input device 170 such as aconventional floppy disk drive or CD-ROM drive accepts via input 172computer program products 174 such as a conventional floppy disk orCD-ROM or other nonvolatile storage media that may be used to transportcomputer instructions or data to the system 150. Computer programproduct 174 has encoded thereon computer readable program code devices176, such as magnetic charges in the case of a floppy disk or opticalencodings in the case of a CD-ROM which are encoded as programinstructions, data or both to configure the computer system 150 tooperate as described below.

In one embodiment, each computer system 150 is a conventional SUNMICROSYSTEMS ULTRA 10 workstation running the SOLARIS operating systemcommercially available from SUN MICROSYSTEMS, Inc. of Mountain View,Calif., a PENTIUM-compatible personal computer system such as areavailable from DELL COMPUTER CORPORATION of Round Rock, Tex. running aversion of the WINDOWS operating system (such as 95, 98, Me, XP, NT or2000) commercially available from MICROSOFT Corporation of Redmond Wash.or a Macintosh computer system running the MACOS or OPENSTEP operatingsystem commercially available from APPLE COMPUTER CORPORATION ofCupertino, Calif. and the NETSCAPE browser commercially available fromNETSCAPE COMMUNICATIONS CORPORATION of Mountain View, Calif. or INTERNETEXPLORER browser commercially available from MICROSOFT above, althoughother systems may be used. In one embodiment, systems may be based onthe conventional MSP430 commercially available from Texas Instruments,Inc., of Dallas, Tex., or the atmega128 commercially available fromAtmel Corporation, of San Jose, Calif., or the PXA xscale commerciallyavailable from Intel Corporation of Santa Clara, Calif. Such systems mayrun the conventional TinyOS, commercially available from the web site ofSourceForge.net or another operating system, such as a real timeoperating system.

FIGS. 2A, 2B and 2C are a flowchart illustrating a method of storing andproviding communications according to one embodiment of the presentinvention. A communication is received and a type of the communicationis identified 210. In one embodiment, the communication is receivedwirelessly.

If the type of the communication identified in step 210 is a request toprovide a previously stored communication 212, the method continues atstep 240 of FIG. 2B. Otherwise 212, the message is a message that shouldbe stored: a current date and time are obtained 214, and a groupcorresponding to the communication is identified 216. In one embodiment,the group corresponding to the communication may be identified via thephysical channel identifier corresponding to the channel on which thecommunication was received, or via a group identifier or channelidentifier that is included with the communication.

In one embodiment, communications that are commands are performed by thedevice if the command has a group identifier corresponding to oneassigned to the device as part of step 216. Referring now to FIG. 2C,the performance portion of step 216 is shown in more detail according toone embodiment of the present invention. A determination is made as towhether the communication is a command capable of being performed 288.In one embodiment, all communications are commands, and step 288 isomitted. If the group of the communication corresponds to at least onegroup assigned to the device that received the communication and thecommunication is a command 290, the command is performed by thereceiving device 292 and otherwise 290, the communication is notperformed by the receiving device 294. The assignment of a device to agroup may be made by way of another command or it may be embedded intothe device at a factory.

Referring again to FIG. 2A, following step 216, step 218 is performed. Adetermination is made as to whether a previous instance of thecommunication received at step 210 is stored 218. In one embodiment, astored communication is a previous instance of a received communicationif both communications have the same sequence number included as part ofthe communication and optionally the same group identifier. The sequencenumber is a unique identifier for each group or unique for all groups,and is included as part of the communication in one embodiment.

If a previous instance of the communication is stored 220, the counterfrom that previous instance is copied, and incremented 222 and theprevious instance is identified for deletion, freeing up storage thathad been occupied by that previous instance and the method continues atstep 226. Otherwise, the counter is initialized 224 and the methodcontinues at step 226.

In one embodiment, no previous instance of any communication may bestored, as each communication is sent only one time. In such embodiment,steps 218-224 are not employed, and step 226 follows step 216.

At step 226, a determination is made as to whether sufficient storageexists after deleting any stored communication for the same group as thereceived communication that has a certain characteristic.

In one embodiment, only the most recent one communication for any groupis stored at any given time, so there will be, at most, onecommunication from the same group to be deleted. The characteristic ofthe communication to be deleted may be that the communication is stored.Thus, if such a stored communication exists, it will be deleted. Otherembodiments may allow more than one communication to be stored for anyone group, for example, because the characteristic is a timestampexceeding a certain age, and the most recently received communicationfor the same group does not have a timestamp that exceeds that age.Determination of which communications to delete can be of anycomplexity.

In one embodiment, the characteristic any communications from the samegroup will meet to be deleted is a timestamp that is the earliest, orone of the earliest among any other timestamps stored with any otherstored communication for the same group as the received communication.In another embodiment, the characteristic is a counter that is thelargest or one of the largest among the counters stored with any otherstored communication for the same group as the received communication.Other criteria may be used to select the communication for deletion. Forexample, of the communications with the top 3 largest counters, one maybe selected for deletion at random or pseudo randomly, to minimize thepossibility that neighboring devices will each delete the same storedcommunication upon receipt of another communication in the same group.In one embodiment, only one communication is identified in this manner,and in another embodiment, there may be multiple communications, as thecharacteristic may include communications having a counter value or agethat exceeds a threshold. In still another embodiment, a functioncombining the timestamp, the current date and time, and number of timesthe communication was received may be used to select the communicationor communications for deletion.

If sufficient storage exists to store the communication after deletingany currently stored communication for the group identified as describedabove and herein 228, any such communication that is stored for thegroup corresponding to the communication received in step 210 andidentified as described above, including a previous instance or adifferent communication, is deleted 230, and the communication receivedin step 210 is stored 232 along with an identifier of the groupcorresponding to that communication, the counter, and the date and timeobtained in step 214, and the method continues at step 210.

It is noted that there may not be sufficient storage to store anincoming communication. This may be because there is less storage thanwould be required to store the most recent communications from eachgroup. This may occur in spite of the fact that a previous communicationis stored for the same group, and will be deleted before thenewly-received communication is stored, because the newly-receivedcommunication may be larger than the one previously stored.

If there is insufficient storage available to store the communicationafter deleting any currently stored communication for the groupcorresponding to the communication identified as described above 238, anattempt is made 234 to identify one or more communications that aremarked in the manner described herein and meets one or morecharacteristics, such as any of those described above. Thecharacteristic or characteristic may be the same or different from anyof those actually used as described above. For example, the oldest oneor more marked communications may be identified, or one or morecommunications with the highest counter values may be identified fordeletion. If such a communication or communications exist 236, suchmarked communication or communications are deleted 238 and the methodcontinues at step 238. The marked communication(s) deleted may includeany marked, or only those from groups different from that of thereceived communication. It is noted that, although for the sake ofillustration the identification of communications to delete and theirdeletion are shown as an iterative process that may repeat until thereis sufficient storage available, in one embodiment rather than repeatinge.g. steps 238 through 238 until sufficient storage is made available,the determination of how many and which communications to delete is madeas part of step 238, and multiple marked communications would be deletedas part of step 238, as one of the characteristics would be the totalsize of the deleted communications are up to at least as large as thespace needed to store the received communication. The function of steps256-260, described below, can similarly be performed in a single passrather than iteratively as shown in this embodiment.

If no such marked communication exists, for example, because there areno marked communications or no marked communications that meet thecriteria 236, the method continues at step 256.

At step 256, an attempt is made to identify any unmarked communicationor communications for one or more groups different from the groupcorresponding to the device receiving the message that have one or morecharacteristics, such as any of those described herein. For example, thecharacteristic may be the oldest one or more communications or the oneor more with the highest counter value or values. The characteristicsused at step 256 may be the same or different from those actually usedas described above. If such one or more communications exists in storage258, the identified communication or communications are deleted 260 andthe method continues at step 238. If no such communication exists instorage 258, an error is indicated 262 and the method continues at step210.

As noted above, the communication received at step 210 may be a requestto provide a stored communication. At step 212, if the type of thecommunication is such a request, the method continues at step 240 ofFIG. 2B.

Referring now to FIG. 2B, at step 240, the group corresponding to therequested communication is identified and compared to the groupcorresponding to the device that received the request. The groupcorresponding to the requested communication may be identifiedexplicitly in the communication, or it may be inferred from the logicalor physical channel used to receive the communication. If that group isthe same as the group of the device receiving the request 242, thecommunication is provided 244, and the method continues at step 210. Thecommunication provided may be implied from the request (e.g. the mostrecent communication corresponding to the group corresponding to therequested communication) or it may be specified, for example, using asequence number corresponding to a communication for that group.

If the group is different from the group of the device receiving therequest 242, the communication is provided and marked as having beensent 246, and the method continues at step 210 of FIG. 2A.

In one embodiment, in addition to, or instead of, marking thecommunication as having been sent, a counter corresponding to the storedcommunication is maintained and the counter is incremented each time thecommunication is sent. The value of that counter may be one of thecharacteristics used as described herein.

System

FIG. 3 is a block schematic diagram of a system for storing andproviding communications according to one embodiment of the presentinvention. Referring now to FIG. 3, at any time, communication receiver320 may receive a communication via radio 310, for example from one ofany number of devices (not shown), any number of which may operate in amanner at least similar to the system shown. In one embodiment, radio310 is a conventional IEEE 802.15.x-compatible radio that provides someor all of the capabilities described by one or more 802.15.xspecifications, and that transmits and receives data over a wirelessnetwork, though wired networks may also be used. Other radios and/orprotocols may be used, such as the conventional 802.11a/b/g/h or othersimilar protocols. When communication receiver 320 receives thecommunication, communication receiver 320 provides the communication tocommunication type identifier 322, in one embodiment along with anidentifier of the channel on which the communication was received.

When communication type identifier 322 receives the communication andany channel identifier, communication type identifier 322 parses thecommunication to identify its type. If the communication is a request toprovide a communication, communication type identifier 322 provides thecommunication and any channel identifier to requested communicationgroup identifier 370, which proceeds as described herein and below.Otherwise, if the communication is not a request, communication typeidentifier 322 provides the communication and the channel identifier togroup identifier 330.

When group identifier 330 receives the communication and the channelidentifier, group identifier 330 requests and receives a current dateand time from operating system 352, and timestamps the communication.Group identifier 330 also determines the group to which thecommunication corresponds. In one embodiment, the channel identifieralso identifies the group corresponding to the communication. In anotherembodiment, group identifier 330 may use a group identifier that isincluded with the communication to identify the group of thecommunication. Group identifier 330 adds the communication, thetimestamp and the identifier of the group to a communication record, andstores the communication record in communication storage 354 on atemporary basis.

Group identifier 330 also determines whether the communicationcorresponds to a group to which the device in which group identifier 330resides also corresponds. In one embodiment, an identifier of the groupcorresponding to the device in which group identifier 330 resides isreceived and stored by device group storage 390, for example from asystem administrator, and group identifier 330 finds that groupidentifier in device group storage 390. In one embodiment, device groupstorage 390 includes conventional disk storage or memory.

If the communication corresponds to the same group as the device, groupidentifier 330 provides a pointer to the communication record to commandexecutor 398, and also provides the pointer to the communication recordto previous instance identifier/deleter 332. Otherwise, group identifier330 provides the pointer to the communication record to previousinstance identifier/deleter 332, which proceeds as described herein andbelow.

When command executor 398 receives the pointer to the communicationrecord, in one embodiment command executor 398 parses the communicationto determine whether it is a command capable of being performed by thedevice in which command executor 398 corresponds. If so, commandexecutor 398 performs the command. Otherwise, in one embodiment commandexecutor 398 takes no action until another communication is received.

When previous instance identifier/deleter 332 receives the pointer tothe communication record from group identifier 330 as described hereinand above, previous instance identifier/deleter 332 checks communicationstorage 354 to determine whether a previous instance of thecommunication corresponding to the record is stored. In one embodiment,communication storage 354 includes conventional memory or disk storage.In one embodiment, each stored communication in communication storage354 is associated with the identifier of the group to which thatcommunication corresponds, the timestamp indicating the last time aninstance of that communication was received, and a counter indicatingthe number of times the communication record was received. In oneembodiment, each communication includes a sequence number, and a storedcommunication is a previous instance of a received communication if bothcommunications have the same sequence number and are associated with thesame group identifier. If identifier/deleter 332 finds a previousinstance of the received communication stored in communication storage354, identifier/deleter 332 copies the timestamp indicating when thatinstance was initially received and the counter associated with theprevious instance, and increments that counter by one. In oneembodiment, identifier/deleter 332 then deletes the previously storedcommunication along with the information associated with thatcommunication, and instead stores the newly received communication incommunication storage 354, associated with the incremented counter, thereceived group identifier, and the timestamp copied as described above.

If identifier/deleter 332 does not find a previous instance of thereceived communication stored in communication storage 354,identifier/deleter 332 initializes a counter in the communicationrecord. In one embodiment, the initialized counter is set equal to one.Identifier/deleter 332 also initializes a mark in the communicationrecord to zero. Identifier/deleter 332 provides the pointer to thecommunication record to storage manager 350.

When storage manager 350 receives the pointer, storage manager 350determines the size of the communication record, and places anindication of the size of the communication record (including theindication) in the record. Storage manager 350 provides the pointer tostorage sufficiency manager 340.

When storage sufficiency manager 340 receives the pointer to thecommunication record, storage sufficiency manager 340 determines whethersufficient storage is available in a permanent area of communicationstorage 354 to store the communication record, after one or morecommunication records including the same group identifier, and matchingone or more predetermined criteria, are deleted from that permanent areaof communication storage 354. In one embodiment, there is at most onlyone stored communication record with the same group identifier as theone in the new communication record, and if such a communication recordis stored, it is identified as the communication record to be deleted.As described herein and above, in another embodiment, the criteria fordeletion is a timestamp that is the or one of the earliest among anyother timestamps included in any other stored communication recordscorresponding to the same group as the new communication record; thatis, the oldest communications are deleted first. In another embodiment,the characteristic is a counter that is the largest or one of thelargest among the counters included in any other stored communicationrecords corresponding to the same group as the new communication record;that is, the communications most commonly received are deleted first.Additional or alternative criteria for deletion may be used in otherembodiments. Storage sufficiency manager 340 provides storage manager350 with an indication of whether or not sufficient storage would beavailable if the communication record or records identified as describedabove were deleted. If insufficient storage would be available, storagesufficiency manager 340 also provides storage manager 350 with the sizeof the storage that would be available after the identifiedcommunication record(s) were deleted.

If storage manager 350 receives the indication that sufficient storageis available, storage manager 350 provides the group identifier to priorgroup communication deleter 342, and prior group communication deleter342 deletes the one or more communication records including the samegroup identifier, and having the predetermined characteristic(s) asdescribed herein and above, from communication storage 354. When priorgroup communication deleter 342 has deleted that communication record orrecords, or if prior group communication deleter 342 determines that nocommunication records including that group identifier are stored, priorgroup communication deleter 342 signals storage manager 350, and storagemanager 350 stores the communication record in a permanent area ofcommunication storage 354. In one embodiment, the system takes nofurther action until a new communication is received by communicationreceiver 320 as described herein and above.

Otherwise, if storage manager 350 receives the indication thatinsufficient storage is available along with the available storage size,storage manager 350 compares the communication record size to theavailable storage size in order to determine the amount of additionalstorage that will be required to store the communication record. If theamount of storage required is greater than the total amount of storagein communication storage 354, storage manager 350 determines that thecommunication record cannot be stored, and in one embodiment discardsthe communication record. Otherwise, storage manager 350 provides theamount of storage required to criteria met marked communicationidentifier 360.

When criteria met marked communication identifier 360 receives theamount of storage required, criteria met marked communication identifier360 identifies the amount of storage that can be freed in communicationstorage 354 by deleting some or all communications that may be marked asdescribed in more detail herein and below. Criteria met markedcommunication identifier 360 flags a number of marked communications incommunication storage 354 for deletion, proceeding in order of thedegree to which the communications meet the criteria for deletion. Forexample, if the criteria for deletion is age, in one embodiment criteriamet marked communication identifier 360 marks the oldest suchcommunication (as indicated by the timestamp included in thecommunication) and proceeds chronologically until enough communicationshave been flagged for deletion to free up the amount of storage requiredor until all marked communications have been flagged. Similarly, if thecriteria for deletion is for example counter value, criteria met markedcommunication identifier 360 marks the communication with the highestcounter value or the first of any such communications with the highestcounter value, and proceeds in descending order of counter value untilenough communications have been flagged for deletion to free up theamount of storage required or until all marked communications have beenflagged. When criteria met marked communication identifier 360 hasflagged the communications, criteria met marked communication identifier360 provides storage manager 350 with an indication of the amount ofstorage that can be freed if all the marked communications are deleted.

When storage manager 350 receives such an indication, storage manager350 compares the amount of storage that can be freed by deleting markedcommunications with the amount of storage required, in order todetermine the amount of additional storage required. If no additionalstorage is required, storage manager 350 signals other groupcommunication deleter 364.

When so signaled, other group communication deleter 364 deletes theflagged communications. When other group communication deleter 364 hasdeleted the flagged communications, other group communication deleter364 signals storage manager 350.

When so signaled, storage manager 350 stores the communication record inthe permanent area of communication storage 354. In one embodiment, thesystem takes no further action until a new communication is received bycommunication receiver 320 as described herein and above.

As described herein and above, criteria met marked communicationidentifier 360 may indicate that the amount of storage that can be freedby deleting marked communications is less than the amount of storagerequired. If storage manager determines additional storage, beyond thatwhich would be freed if all of the marked communications were deleted,is required to store the communication record, storage manager 350provides the amount of additional storage required to criteria metunmarked communication identifier 362.

When criteria met unmarked communication identifier 362 receives theamount of additional storage required, criteria met unmarkedcommunication identifier 362 finds the group identifier stored in devicegroup storage 390, and identifies the amount of storage that can befreed in communication storage 354 by deleting unmarked communicationsassociated with group identifiers other than that group identifier.

If criteria met unmarked communication identifier 362 determines thatthe amount of storage that can be freed in communication storage 354 bydeleting communications associated with groups other than the groupidentified in device group storage 390 is less than the amount ofadditional storage required, criteria met unmarked communicationidentifier 362 unmarks the communications marked as described above, andso indicates to storage manager 350. In one embodiment, when storagemanager 350 receives such an indication, storage manager 350 determinesthat the communication cannot be stored, and discards the communicationand associated information.

Otherwise, if criteria met unmarked communication identifier 362determines that the amount of storage that can be so freed is equal toor greater than the amount of additional storage required, criteria metunmarked communication identifier 362 flags for deletion incommunication storage 354 a number of unmarked communications associatedwith group identifiers other than the group identifier stored in devicegroup storage 390, proceeding in order of the degree to which thosecommunications meet the criteria for deletion as described herein andabove, until enough communications have been flagged for deletion tofree up the amount of additional storage required. When criteria metunmarked communication identifier 362 has flagged such communications,criteria met unmarked communication identifier 362 signals other groupcommunication deleter 364.

When so signaled, other group communication deleter 364 deletes theflagged communications. When other group communication deleter 364 hasdeleted the flagged communications, other group communication deleter364 signals storage manager 350.

When so signaled, storage manager 350 stores the timestampedcommunication, associated with the group identifier and the counter, inthe permanent area of communication storage 354. In one embodiment, thesystem takes no further action until a new communication is received bycommunication receiver 320 as described herein and above.

As described herein and above, if communication type identifier 322determines that the communication is a request, communication typeidentifier 322 provides the request to requested communication groupidentifier 370 along with any channel identifier. When requestedcommunication group identifier 370 receives the request and any channelidentifier, requested communication group identifier 370 identifies thegroup to which the requested communication corresponds, as describedherein and above. When requested communication group identifier 370 hasidentified the group to which the requested communication corresponds,requested communication group identifier 370 provides the groupidentifier to communication rebroadcast manager 380, which proceeds asdescribed herein and below. Requested communication group identifier 370also checks the group identifier stored in device group storage 390 inorder to determine whether the requested communication corresponds tothe same group as the device in which requested communication groupidentifier 370 resides. If the groups are not the same, requestedcommunication group identifier 370 provides the identifier of the groupto which the requested communication corresponds to mark manager 382,which proceeds as described herein and below.

In the embodiment that more than one communication for each group isstored at any given time, requested communication group identifier 370also identifies the communication requested. As described herein andabove, each communication may for example be identified by the sequencenumber and group identifier of the communication, and in one embodiment,the sequence number of any requested communication may be included inthe request. Other techniques for identifying requested communicationsmay be used in other embodiments. In this embodiment, in addition toproviding the group identifier to mark manager 382 and/or communicationrebroadcast manager 380, requested communication group identifier 370also provides the sequence number of the requested communication.

When communication rebroadcast manager 380 receives the group identifierand optionally the sequence number, communication rebroadcast manager380 finds the communication in communication storage 354 correspondingto that group and including that sequence number, if one was received,and communication rebroadcast manager 380 broadcasts that communicationvia radio 310. If no such communication is stored in communicationstorage 354, in one embodiment communication rebroadcast manager 380takes no further action to broadcast the communication.

When mark manager 382 receives the group identifier and optionally thesequence number as described herein and above, mark manager 382 findsthe communication in communication storage 354 corresponding to thatgroup and including that sequence number, if one was received, and marksthat communication. If no such communication is stored in communicationstorage 354, in one embodiment mark manager 382 takes no further actionto mark the communication.

SUMMARY

There has been disclosed:

A method of, and computer program product for, storing a communication,including wirelessly receiving the communication, identifying a groupcorresponding to the communication, determining whether sufficientstorage exists to store the communication or does not exist to store thecommunication, provided that at least zero stored communicationscorresponding to the group identified are deleted, responsive to adetermination that sufficient storage does not exist to store thecommunication, identifying at least zero stored communications that havebeen wirelessly provided by a device that received the communication inresponse to at least one request to provide such a stored communication,and that correspond to at least one first characteristic, responsive tothe at least zero stored communications comprising at least one storedcommunication, deleting the at least one stored communicationidentified; and storing the communication received and the groupidentified.

There is an optional feature, whereby at least one of the at least onefirst characteristic is related to a time of receipt of each of the atleast zero stored communications that have been wirelessly provided.

There is an optional feature, whereby at least one of the at least onefirst characteristic is related to a number of times an instance of eachof the at least zero stored communications that have been wirelesslyprovided was received.

Optionally, the method and computer program product additionallyinclude, responsive to a size of the communication received exceeding asize of the at least zero stored communications identified, identifyingat least one stored communication that has not been wirelessly providedby the device that received the communication in response to at leastone request to provide such at least one stored communication and thatcorrespond to at least one second characteristic, and deleting the atleast one stored communication that has not been wirelessly provided bythe device that received the communication identified before the storingstep.

There is an optional feature, whereby at least one of the at least onesecond characteristic is related to a time of receipt of each of the atleast zero stored communications that have been wirelessly provided.

There is an optional feature, whereby at least one of the at least onesecond characteristic is related to a number of times an instance ofeach of the at least zero stored communications that have beenwirelessly provided was received.

There is an optional feature, whereby the at least zero storedcommunications corresponding to the group comprises at least one storedcommunications corresponding to the group; and the method and computerprogram product may additionally include deleting the at least onestored communication corresponding to the group.

There has been disclosed a system for storing a communication, includinga communication receiver having an input operatively coupled forreceiving the communication from a wireless radio, the communicationreceiver for providing the communication at an output, the communicationcomprising an indication of a group, a group identifier having an inputcoupled to the communication receiver output, the group identifier foridentifying the group to which the indication corresponds and forproviding at an output an identifier of the group, a storage sufficiencymanager having a communication input coupled to the communicationreceiver output for receiving the communication and a group inputcoupled to the group identifier output for receiving the identifier ofthe group, the storage sufficiency manager for determining whethersufficient storage exists in at least a portion of a storage devicecoupled to an input/output to store the communication or does not existin the at least the portion of the storage device to store thecommunication, provided that at least zero stored communicationscorresponding to the group identifier received at the group input aredeleted and for providing at an output an indication related to whethersaid sufficient storage exists in the at least the portion of thestorage device, a marked communication identifier having an inputcoupled to the storage sufficiency manager output for receiving theindication, the marked communication identifier for, responsive to theindication indicating that sufficient storage does not exist to storethe communication in the at least the portion of the storage device,providing at an output a first identification of at least zero storedcommunications stored in the at least the portion of the storage devicethat have been wirelessly provided by a device comprising the system inresponse to at least one request to provide such a stored communication;and that correspond to at least one first characteristic, an other groupcommunication deleter having an input coupled to the markedcommunication identifier output for receiving the first identificationof at least zero stored communications stored in the at least theportion of the storage device, the other group communication deleterfor, responsive to the at least zero stored communications comprising atleast one stored communication, deleting via a first output coupled tothe at least the portion of the storage device the at least one storedcommunication corresponding to the first identification and providing asignal at a second output; and a storage manager having a first inputcoupled to the storage sufficiency manager output for receiving theindication, a second input coupled to the other group communicationdeleter for receiving the signal, a third input coupled to thecommunication receiver output for receiving the communication received,and a fourth input coupled to the group identifier for receiving theidentifier of the group, the storage manager for, responsive to receiptof the signal or receipt of the indication indicating that sufficientstorage does not exist to store the communication in the at least theportion of the storage device, storing via an output the communicationreceived and the group identified in the at least the portion of thestorage device.

There is an optional feature, whereby at least one of the at least onefirst characteristic is related to a time of receipt of each of the atleast zero stored communications that have been wirelessly provided.

There is an optional feature, whereby at least one of the at least onefirst characteristic is related to a number of times an instance of eachof the at least zero stored communications that have been wirelesslyprovided was received.

There is an optional feature, whereby the storage sufficiency manager isadditionally for identifying a shortfall amount of storage in thestorage device, provided that at least zero stored communicationscorresponding to the group identifier received at the group input aredeleted, the indication provided at the storage sufficiency manageroutput comprises the shortfall amount, the marked communicationidentifier is additionally for determining whether an amount of storagecorresponding to the at least zero communications identified is not aslarge as the shortfall amount, and for providing a notice responsive tothe determination, and the system additionally may include an unmarkedcommunication identifier having an input coupled to the markedcommunication identifier output, the unmarked communication identifierfor, responsive to the notice, providing at an output a secondidentification of at least one stored communications stored in the atleast the portion of the storage device that have not been wirelesslyprovided by a device comprising the system in response to at least onerequest to provide such a stored communication, and that correspond toat least one second characteristic; and there is an optional feature,whereby the other group communication deleter input is coupled to theunmarked communication identifier output for additionally receiving thesecond identification of the at least one stored communications storedin the at least the portion of the storage device, the other groupcommunication deleter additionally for deleting via the first outputcoupled to the at least the portion of the storage device the at leastone stored communication corresponding to the second identification.

There is an optional feature, whereby at least one of the at least onesecond characteristic is related to a time of receipt of each of the atleast zero stored communications that have been wirelessly provided.

There is an optional feature, whereby at least one of the at least onesecond characteristic is related to a number of times an instance ofeach of the at least zero stored communications that have beenwirelessly provided was received.

There is an optional feature, whereby the at least zero storedcommunications corresponding to the group comprises at least one storedcommunications corresponding to the group, and the system additionallyincludes a prior group communication deleter having an input coupled tothe group identifier output for receiving the group identifier, theprior group communication deleter for deleting, via an input/outputcoupled to the at least the portion of the storage device, the at leastone stored communication corresponding to the group.

What is claimed is:
 1. A method of enabling a network device to exchangecommunications addressed to a group using a group identifier in asequence of transmissions, the method comprising: receiving a firstcommunication addressed to a group of network devices; identifying agroup identifier corresponding to the communication; determining whethera set of stored communications stored in a storage module include thegroup identifier; responsive to a determination that the set of storedcommunications include the group identifier, increasing a counterassociated with each of the stored communications in the set by one;determining whether sufficient storage exists in the storage module tostore the first communication; and responsive to a determination thatsufficient storage does not exist in the storage module to store thefirst communication: identifying a previously stored secondcommunication that: has been provided by the device that received thefirst communication in response to at least one request, and has anassociated counter with the greatest counter value; deleting the secondcommunication; and storing the first communication.
 2. The method ofclaim 1 wherein a group identifier of the second communicationcorresponds to the group identifier of the first communication.
 3. Themethod of claim 1, further comprising: determining that a previousinstance of the first communication is not stored in the network device;initializing a counter to one; and associating the counter with thefirst communication.
 4. The method of claim 2, further comprising:determining that the second communication cannot be identified;identifying a previously stored third communication that: is associatedwith a group identifier different from the group identifiercorresponding to the first communication, and has the greatest countervalue; deleting the third communication; and storing the firstcommunication.
 5. The method of claim 2, further comprising: responsiveto a size of the first communication received exceeding a size of thesecond communication: identifying a previously stored thirdcommunication that: is associated with a group identifier different fromthe group identifier corresponding to the first communication, and hasthe greatest counter value; deleting the third communication; andstoring the first communication.
 6. The method of claim 1, furthercomprising: responsive to a size of the first communication receivedexceeding a size of the second communication: identifying a previouslystored third communication that has not been provided by the device thatreceived the communication in response to at least one request toprovide such at least one stored communication and that correspond to atleast one second characteristic; and deleting the third communicationthat has not been provided by the device before the storing step.
 7. Themethod of claim 6 wherein the at least one second characteristic isrelated to a time of receipt.
 8. The method of claim 6 wherein the atleast one second characteristic is related to a number of times aninstance of the third communication was received.
 9. A system configureto enable a network device to exchange communications address to a groupusing a group identifier in a sequence of transmissions, the systemcomprising: a processor; and instructions that when executed on theprocessor cause the processor to perform operations that include:receiving a first communication addressed to a group of network devices;identifying a group identifier corresponding to the communication;determining whether a set of stored communications stored in a storagemodule include the group identifier; responsive to a determination thatthe set of stored communications include the group identifier,increasing a counter associated with each of the stored communicationsin the set by one; determining whether sufficient storage exists in thestorage module to store the first communication; and responsive to adetermination that sufficient storage does not exist in the storagemodule to store the first communication: identifying a previously storedsecond communication that: has been provided by the device that receivedthe first communication in response to at least one request, and has anassociated counter with the greatest counter value; deleting the secondcommunication; and storing the first communication.
 10. The system ofclaim 9 wherein a group identifier of the second communicationcorresponds to the group identifier of the first communication.
 11. Thesystem of claim 9, further comprising: determining that a previousinstance of the first communication is not stored in the network device;initializing a counter to one; and associating the counter with thefirst communication.
 12. The system of claim 10, further comprising:determining that the second communication cannot be identified;identifying a previously stored third communication that: is associatedwith a group identifier different from the group identifiercorresponding to the first communication, and has the greatest countervalue; deleting the third communication; and storing the firstcommunication.
 13. The system of claim 10, further comprising:responsive to a size of the first communication received exceeding asize of the second communication: identifying a previously stored thirdcommunication that: is associated with a group identifier different fromthe group identifier corresponding to the first communication, and hasthe greatest counter value; deleting the third communication; andstoring the first communication.
 14. The system of claim 9, furthercomprising: responsive to a size of the first communication receivedexceeding a size of the second communication: identifying a previouslystored third communication that has not been provided by the device thatreceived the communication in response to at least one request toprovide such at least one stored communication and that correspond to atleast one second characteristic; and deleting the third communicationthat has not been provided by the device before the storing step. 15.The system of claim 14 wherein the at least one second characteristic isrelated to a number of times an instance of the second communicationthat have been provided was received.
 16. A computer program stored on anon-transitory computer readable medium configured to enable a networkdevice to exchange communications addressed to a group using groupidentifier in a sequence of transmissions, the computer programcomprising: instructions that when executed on a processor cause theprocessor to perform operations that include: receiving a firstcommunication addressed to a group of network devices; identifying agroup identifier corresponding to the communication; determining whethera set of stored communications stored in a storage module include thegroup identifier; responsive to a determination that the set of storedcommunications include the group identifier, increasing a counterassociated with each of the stored communications in the set by one;determining whether sufficient storage exists in the storage module tostore the first communication; and responsive to a determination thatsufficient storage does not exist in the storage module to store thefirst communication: identifying a previously stored secondcommunication that: has been provided by the device that received thefirst communication in response to at least one request, and has anassociated counter with the greatest counter value; deleting the secondcommunication; and storing the first communication.
 17. The computerprogram of claim 16 wherein a group identifier of the secondcommunication corresponds to the group identifier of the firstcommunication.
 18. The system of claim 16, further comprising:determining that a previous instance of the first communication is notstored in the network device; initializing a counter to one; andassociating the counter with the first communication.
 19. The system ofclaim 17, further comprising: determining that the second communicationcannot be identified; identifying a previously stored thirdcommunication that: is associated with a group identifier different fromthe group identifier corresponding to the first communication, and hasthe greatest counter value; deleting the third communication; andstoring the first communication.
 20. The system of claim 17, furthercomprising: responsive to a size of the first communication receivedexceeding a size of the second communication: identifying a previouslystored third communication that: is associated with a group identifierdifferent from the group identifier corresponding to the firstcommunication, and has the greatest counter value; deleting the thirdcommunication; and storing the first communication.